1. Field of the Invention
This invention is directed toward an improved cutter bar for use in felling heads on tree harvesting machines.
2. Description of the Prior Art
Tree harvesting machines have normally employed shears or saws to cut through trees being harvested. Both devices have disadvantages however. It has been proposed to use cylindrical cutter bars, rotating about their longitudinal axis, to cut through trees. Such cutter bars are lighter in weight and have lower power requirements than the shear or saw arrangements.
The known cutter bars have their own disadvantages however. The initial cutter bars used had teeth extending across the cylindrical surface of the bar in a direction parallel to the longitudinal axis of the bar. As each tooth began cutting, the tooth exerted a reactive force on the felling head raising or lowering it depending on the direction of rotation of the bar. This presented problems in getting a strain cut across the tree and also resulted in vibration causing heavy wear on the bearings supporting the cutter bar during rotating and cutting.
To minimize the vibration and wear problems encountered using straight cutting teeth it has been proposed to use one or more cutting teeth formed in continuous spirals over the cutter bar. Such teeth minimize vibration and reduce wear on the bearings. However it is difficult to expel the chips from these cutter bars particularly when cutting through large trees. The cutter bars with continuous spiral teeth have a tendency to plug up and the cutting operation must be interrupted to clean the teeth.